This invention relates to the synthesis of symmetrical diphosphatetraazacyclooctatetraenes and to novel eight-membered ring heterocyclic compounds produced thereby. More particularly, this invention concerns itself with a novel method for synthesizing 1,5-diphospha-2,4,6,8-tetraazacyclooctatetraenes. The resulting products exhibit excellent antioxidant and anticorrosion characteristics making them excellent candidates for use as additives in engine oils, hydraulic fluids and greases as well as in other applications apparent to those skilled in the art.
Present interest in the utilization of perfluorinated fluids for high temperature lubricant applications has provided an impetus in a research effort directed toward the discovery of antioxidant and anticorrosive additives. Because of their thermal stability, the perfluorinated fluids have a great potential for use in lubrication and hydraulic applications. However, there is a serious drawback in their use resulting from the fact that certain metals present in aircraft components tend to corrode and degrade the fluids being used as lubricants. This occurs at temperatures above 550.degree. F. in an oxidative environment.
It would be highly desirable, therefore, to provide an additive for the perfluorinated fluids that would overcome the degradation and corrosion problems associated with their use. As a consequence, a considerable research effort has evolved in an attempt to provide such additives and an efficient and convenient method for their synthesis. As a result of this effort, it has been found that symmetrical diphosphatetraazacyclooctatetraenes can be obtained by effecting a reaction between a perfluoroalkylether amidine and a trihalophosphorane. The corrosion problems encountered when using perfluorinated fluid lubricants are obviated by using the additives of this invention.